CONCLUSIONS
The physicochemical properties and the activated carbon adsorbability of released NOM from eight different forest and agricultural soils were investigated. Based on the results obtained, the conclusions can be drawn as follows:
In Chapter 3, the basic characteristics of released NOM were investigated and the results showed that the average content of OM followed the order of soil origin: VF (vegetable field) < PF (paddy field) < BF (broadleaf forest) < CF (coniferous forest), and the release potential of NOM was significantly influenced by pH conditions rather than the soil origins and the OM content. The concentration of released NOM under basic condition was tens of times larger than that under neutral and acidic conditions. The DOC-based mass concentration percentages of the released NOM under neutral condition estimated based on the fluorescence EEM images were: humic acids (12.4-49.9%), fulvic acids (25.0-81.7%) and protein like substances (3.2-25.1%), showing significant composition variations with the soil origins.
In Chapter 4, the adsorption behavior and adsorption strength of the released NOM were evaluated. The residual concentration of NOM assessed with the overall concentration indices (DOC and UV260) and the florescence intensity (FI) of three fluorescent components (P1, P2 and P3) after adsorption varied greatly with the soil origins.
Humic substances (P1 and P2) were gradually removed by AC, but the protein-like substances (P3) could not be adsorbed completely even when the AC dose was increased to 5 g/L. The adsorption of organic species with larger MW size was more preferable than that with relatively smaller MW size. The application of modified Freundlich model for describing the adsorption of released NOM from different soil origins was acceptable and the use of fluorescent components for the adsorption analysis of NOM provided new information for better understanding the heterogeneity of NOM in their adsorbability. The adsorption strength of released NOM from agricultural soils obtained based on three
104
fluorescent components was higher than that from forest soils.
In Chapter 5, as the releasing condition changed from acidic to basic, more NOM components possessing larger UV absorbing capability and larger MW were released into water. The modified Freundlich isotherm model was more effective in describing the adsorption isotherms of the released NOM than Langmuir and Freundlich models. Based on the batch adsorption experiments and isotherm data analysis with modified Freundlich isotherm model, the released NOM under neutral condition was found to possess higher adsorbability.
In Chapter 6, humic acids were found more adsorbable than fulvic acids and then followed by protein-like substances. The adsorption strength of NOM differed greatly with the ACs used, and carbon G was the most available AC for removing humic substances contained in released NOM, while carbon B was more effective in adsorbing organic species reflected by UV260. The adsorption strength of the humic acids and fulvic acids could be estimated from the K values assessed with the overall quality index of DOC.
In Chapter 7, the correlations of adsorption strength (K) with the properties of released NOM and ACs were investigated based on the magnitude of the correlation coefficient (R2) obtained through linear regression analysis. The adsorption strength of the released NOM was influenced not only by the characteristic of released NOM, but also by the properties of ACs. The pores with size above 30 Å was found more effective for adsorption of humic substances, while, the pores with size below 30 Å was more effective for the removal of protein-like substances.
The findings of the study relating to this dissertation will benefit to better understanding of the physicochemical characteristics of released NOM from different soil origins, and to determination of optimal adsorption conditions for removal of NOM.
105
REFERENCES
1) Ahmad, A.A., Hameed, B.H., 2009. Reduction of COD and color of dyeing effluent from a cotton textile mill by adsorption onto bamboo-based activated carbon. J.
Hazard. Mater. 172(2), 1538-1543.
2) Amat, A.M., Arques, A., García-Ripoll, A., Santos-Juanes, L., Vicente, R., Oller, I., Maldonado, M.I., Malato, S., 2009. A reliable monitoring of the biocompatibility of an effluent along an oxidative pre-treatment by sequential bioassays and chemical analyses. Water Res. 43(3), 784-792.
3) Amy, G.L., Sierka, R.A., Bedessem, J., Price, D., Tan, L., 1992. Molecular size distributions of dissolved organic matter. J. Am. Water Works. Ass. 84, 67-75.
4) Apul, O.G., Wang, Q.L., Zhou, Y., Karanfil, T., 2013. Adsorption of aromatic organic contaminants by graphene nanosheets: Comparison with carbon nanotubes and activated carbon. Water Res. 47(4), 1648-1654.
5) Aschermann, G., Jeihanipour, A., Shen, J., Mkongo, G., Dramas, L., Croué, J. P., Schäfer, A., 2016. Seasonal variation of organic matter concentration and characteristics in the Maji ya Chai River (Tanzania): Impact on treatability by ultrafiltration. Water Res. 101, 370-381.
6) Avena, M.J., Koopal, L.K., 1998. Desorption of humic acids from an iron oxide surface. Environ. Sci. Technol. 32, 2572-2577.
7) Baghoth, S.A., Sharma, S.K., Amy, G.L., 2011. Tracking natural organic matter (NOM) in a drinking water treatment plant using fluorescence excitation-emission matrices and PARAFAC. Water Res. 45(2), 797-809.
8) Baker, A., 2001. Fluorescence excitation-emission matrix characterization of some sewage-impacted rivers. Environ. Sci. Technol. 35(5), 948-953.
9) Baker, A., 2002. Fluorescence excitation-emission matrix characterization of river waters impacted by a tissue mill effluent. Environ. Sci. Technol. 36(7), 1377-1382.
10) Bell, N.G.A., Murray, L., Graham, M.C., Uhrin, D., 2014. NMR methodology for complex mixture ‘separation’. Chem. Commun. 50 (14), 1694-1697.
11) Bhatnagar, A., Hogland, W., Marques, M., Sillanpää, M., 2013. An overview of the
106
modification methods of activated carbon for its water treatment applications.
Chem. Eng. J. 219, 499-511.
12) Carstea, E.M., Bridgeman, J., Baker, A., Reynolds, D.M., 2016. Fluorescence spectroscopy for wastewater monitoring: A review. Water Res. 95, 205-219.
13) Celik, I., 2005. Land-use effects on organic matter and physical properties of soil in a southern Mediterranean highland of Turkey. Soil Till. Res. 83(2), 270-277.
14) Chen, M., Hur, J., 2015. Pre-treatments, characteristics, and biogeochemical dynamics of dissolved organic matter in sediments: a review. Water Res. 79, 10-25.
15) Chen, W., Westerhoff, P., Leenheer, J.A., Booksh, K., 2003. Fluorescence excitation-emission matrix regional integration to quantify spectra for dissolved organic matter. Environ. Sci. Technol. 37(24), 5701-5710.
16) Collins, M.R., Amy, G.L., Steelink, C., 1986. Molecular weight distribution, carboxylic acidity and humic substances content of aquatic organic matter:
implications for removal during water treatment. Environ. Eng. Sci. 20, 1028-1032.
17) Crittenden, J.C., Luft, P., Hand, D.W., 1985. Prediction of multicomponent adsorption equilibria in background mixtures of unknown composition. Water Res.
19(12), 1537-1548.
18) Dąbrowski, A., Podkościelny, P., Hubicki, Z., Barczak, M., 2005. Adsorption of phenolic compounds by activated carbon-a critical review. Chemosphere 58(8), 1049-1070.
19) Dolas, H., Sahin, O., Saka, C., Demir, H., 2011. A new method on producing high surface area activated carbon: The effect of salt on the surface area and the pore size distribution of activated carbon prepared from pistachio shell. Chem. Eng. J.
166(1), 191-197.
20) Dudal, Y., Sevenier, G., Dupont, L., Guillon, E., 2005. Fate of the metal-binding soluble organic matter throughout a soil profile. Soil Sci. 170, 707-715.
21) Dudgeon, D., Arthington, A.H., Gessner, M.O., Kawabata, Z.I., Knowler, D.J., Lévêque, C., Naiman, R.J., Prieur-Richard, A.H., Soto, D., Stiassny, M.L.J., Sullivan, C.A., 2006. Freshwater biodiversity: importance, threats, status and conservation challenges. Biol. Rev. 81(02), 163-182.
107
22) Ebie, K., Li, F., Azuma, Y., Yuasa, A., Hagishita, T., 2001. Pore distribution effect of activated carbon in adsorbing organic micropollutants from natural water. Water Res. 35(1), 167-179.
23) El-Naas, M.H., Al-Zuhair, S., Alhaija, M.A., 2010. Reduction of COD in refinery wastewater through adsorption on date-pit activated carbon. J. Hazard. Mater.
173(1), 750-757.
24) Graeber, D., Gelbrecht, J., Pusch, M.T., Anlanger, C., Schiller, D., 2012.
Agriculture has changed the amount and composition of dissolved organic matter in Central European headwater streams. Sci. Total Environ. 438, 435-446.
25) Grybos, M., Davranche, M., Gruau, G., Petitjean, P., Pédrot, M., 2009. Increasing pH drives organic matter solubilization from wetland soils under reducing conditions. Geoderma 154(1), 13-19.
26) Gu, B., Schmitt, J., Chen, Z., Liang, L., McCarthy, J.F., 1995. Adsorption and desorption of different organic matter fractions on iron oxide. Geochim.
Cosmochim. Acta 59(2), 219-229.
27) Gui, H., Du, H., Li, F., Wei, Y., Yamada. T., 2015. Characteristics of NOM released from soil under different pH conditions: physicochemical properties and activated carbon adsorbability. Journal of Japan Society of Civil Engineers, Ser.G (Environmental Research) 71(7), 315-322.
28) Guigue, J., Lévêque, J., Mathieu, O., Schmitt-Kopplin, P., Lucio, M., Arrouays, D., Jolivet, C., Dequiedt, S., Chemidlin Orévost-Bouré, N., Ranjard, L., 2015. Water-extractable organic matter linked to soil physico-chemistry and microbiology at the regional scale. Soil Biol. Biochem. 84, 158-167.
29) Haynes, R.J., Donald, L.S., 2005. Labile organic matter fractions as central components of the quality of agricultural soils: an overview. Adv. Agron. 85, 221-268.
30) Haynes, R.J., Naidu, R., 1998. Influence of lime, fertilizer and manure applications on soil organic matter content and soil physical conditions: a review. Nutr. Cycl.
Agroecosys 51(2), 23-137.
31) Hood, E., Fellman, J., Spencer, R.G., Hernes, P.J., Edwards, R., D’Amore, D., Scott, D., 2009. Glaciers as a source of ancient and labile organic matter to the
108
marine environment. Nature 462(7276), 1044-1047.
32) Huang, H., Chow, C.W.K. Jin, B., 2016. Characterisation of dissolved organic matter in stormwater using high-performance size exclusion chromatography.
Journal of Environmental Sciences 42, 236-245.
33) Hudson, N., Bake, A. and Reynolds, D., 2007. Fluorescence analysis of dissolved organic matter in natural, waste and polluted waters-a review. River. Res. Applic.
23, 631-649.
34) Hyung, H., Kim, J.H., 2008. Natural organic matter (NOM) adsorption to multi-walled carbon nanotubes: effect of NOM characteristics and water quality parameters. Environ. Sci. Technol. 42(12), 4416-4421.
35) Jaffé, R., McKnight, D., Maie, N., Cory, R., McDowell, W.H., Campbell, J.L., 2008. Spatial and temporal variations in DOM composition in ecosystems: the importance of long-term monitoring of optical properties. J. Geophys. Res. 113 (G4).
36) Kaiser, K., Guggenberger, G., 2000. The role of DOM sorption to mineral surfaces in the preservation of organic matter in soils. Org. Geochem. 31, 711-725.
37) Kalibbala, H.M., Kaggwa, R., Wahlberg, O. and Plaza, E., 2011. Characteristics of natural organic matter and formation of chlorination by-products at Masaka waterworks. Journal of water supply and technology-AQUA 60 (8), 511-519.
38) Karanfil, T., Kilduff, J.E., Schlautman, M.A., Weber, W.J., 1996. Adsorption of organic macromolecules by granular activated carbon. 1. Influence of molecular properties under anoxic solution conditions. Environ. Sci. Technol. 30(7), 2187-2194.
39) Kent, F.C., Montreuil, K.R., Stoddart, A.K., Reed, V.A., Gagnon, G.A., 2014.
Combined use of resin fractionation and high performance size exclusion chromatography for characterization of natural organic matter. J. Environ. Sci.
Heal. A 49(14), 1615-1622.
40) Kilduff, J.E., Karanfil, T., Chin, Y.P., Weber, W.J., 1996. Adsorption of natural organic polyelectrolytes by activated carbon: a size-exclusion chromatography study. Env. Sci. Tec. 30(4), 1336-1343.
41) Korshin, G., Chow, C.W.K, Fabris, R., Drikas, M., 2009. Absorbance
109
spectroscopy-based examination of effects of coagulation on the reactivity of fractions of natural organic matter with varying apparent molecular weights. Water Res. 43(6), 1541-1548.
42) Lamar, R.T., Olk, D.C., Mayhew, L., Bloom, P.R., 2014. A new standardized method for quantification of humic and fulvic acids in humic ores and commercial products. J. Aoac. Int. 97(3), 721-730.
43) Langmuir, I., 1918. The adsorption of gases on plane surfaces of glass, mica and platinum. J. Am. Chem. Soc. 40(9), 1361-1403.
44) Lee, B.M., Seo, Y.S., Hur, J., 2015. Investigation of adsorptive fractionation of humic acid on graphene oxide using fluorescence EEM-PARAFAC. Water Res. 73, 242-251.
45) Lee, N., Amyb, G., Croue, J.P., 2006. Low-pressure membrane (MF/UF) fouling associated with allochthonous versus autochthonous natural organic matter. Water Res. 40, 2357-2368.
46) Leenheer, J.A., Croué, J.P., 2003. Peer reviewed: characterizing aquatic dissolved organic matter. Environ. Sci. Technol. 37(1), 18-26.
47) Li, F., Yuasa, A., Chiharada, H., Matsui, Y., 2003. Storm impacts upon the composition of organic matrices in Nagara River-a study based on molecular weight and activated carbon adsorbability. Water Res. 37(16), 4027-4037.
48) Li, F., Yuasa, A., Ebie, K., Azuma, Y., Hagishita, T., Matsui, Y., 2002. Factors affecting the adsorption strength of dissolved organic matter onto activated carbon:
modified isotherm analysis. Water Res. 36(18), 4592-4604.
49) Li, F., Yuasa, A., Muraki, Y., Matsui, Y., 2005. Impacts of a heavy storm of rain upon dissolved and particulate organic C, N and P in the main river of a vegetation-rich basin area in Japan. Sci. Total. Environ. 345(1), 99-113.
50) Li, W., Chen, S., Xu, Z., Li, Y., Shuang, C., Li, A., 2014. Characterization of dissolved organic matter in municipal wastewater using fluorescence PARAFAC analysis and chromatography multi-excitation/emission scan: a comparative study.
Environ. Sci. Technol. 48 (5), 2603-2609.
51) Li, W., Xu, Z., Li, A., Wu, W., Zhou, Q., Wang, J., 2013. HPLC/HPSEC-FLD with multi-excitation/emission scan for EEM interpretation and dissolved organic matter
110 analysis. Water Res. 47, 1246-1256.
52) Liu, S.L., An, N.N., Yang, J.J., Dong, S.K., Wang, C., Yin, Y.J., 2015. Prediction of soil organic matter variability associated with different land use types in mountainous landscape in southwestern Yunnan province, China. Catena 133, 137-144.
53) Liu, T., Chen, Z.L., Yu, W.Z., You, S.J., 2011. Characterization of organic membrane foulants in a submerged membrane bioreactor with pre-ozonation using three-dimensional excitation-emission matrix fluorescence spectroscopy. Water Res. 45, 2111-2121.
54) Malcolm, R.L., 1990. The uniqueness of humic substances in each of soil, stream and marine environments. Anal. Chim. Acta 1990, 232, 19-30.
55) Martinez, C.E., Jacobson, A.R., McBride, M.B., 2003. Aging and temperature effects on DOC and elemental release from a metal contaminated soil. Environ.
Pollut. 122, 135-143.
56) Masscheleyn, P.H., Delaune, R.D., Patrick Jr., W.H., 1991. Effect of redox potential and pH on arsenic speciation and solubility in a contaminated soil.
Environ. Sci. Technol. 25(8), 1414-1419.
57) Matilainen, A., Lindqvist, N., Korhonen, S., Tuhkanen, T., 2002. Removal of NOM in the different stages of the water treatment process. Environment International 28(6), 457-465.
58) Matilainen, A., Vepsäläinen, M., Sillanpää, M., 2010. Natural organic matter removal by coagulation during drinking water treatment: a review. Sci. Adv.
Colloid Interface Sci. 159(2), 189-197.
59) McCreary, J.J., Snoeyink, V.L., 1980. Characterization and activated carbon adsorption of several humic substances. Water Res. 14(2), 151-160.
60) McDonald, S., Bishop, A.G., Prenzler, P.D., Robards, K., 2004. Analytical chemistry of freshwater humic substances. Anal. Chim. Acta 527, 105-124.
61) Nelson, P.N., Baldock, J.A., Oades, J.M., 1992. Concentration and composition of dissolved organic carbon in streams in relation to catchment soil properties.
Biogeochemistry 19(1), 27-50.
62) Ohno, T., Amirbahman, A., Bro, R., 2007. Parallel factor analysis of
excitation-111
emission matrix fluorescence spectra of water soluble soil organic matter as basis for the determination of conditional metal binding parameters. Environ. Sci.
Technol. 42(1), 186-192.
63) Pagano, T., Bida, M., Kenny, J.E., 2014. Trends in levels of allochthonous dissolved organic carbon in natural water: a review of potential mechanisms under a changing climate. Water 6(10), 2862-2897.
64) Potschka M., 1993. Mechanism of size-exclusion chromatography. J Chromatogr 648, 41-69.
65) Qin, X., Liu, F., Wang, G., Hou, H., Li, F., Weng, L., 2015. Fractionation of humic acid upon adsorption to goethite: Batch and column studies. Biochem. Eng. J. 269, 272-278.
66) Quinones, I., Guiochon, G., 1998. Extension of a Jovanovic–Freundlich isotherm model to multicomponent adsorption on heterogeneous surfaces. J. Chromatogr. A 796(1), 15-40.
67) Rivera-Utrilla, J., Sánchez-Polo, M., Gómez-Serrano, V., Alvarez, P.M., Alvim-Ferraz, M.C.M., Dias, J.M., 2011. Activated carbon modifications to enhance its water treatment applications. An overview. J. Hazard. Mater. 187(1), 1-23.
68) Sakurovs, R., Lewis, C., Wibberley, L., 2016. Effect of heat and moisture on surface titratability and pore size distribution of Victorian brown coals. Fuel 172, 124-129.
69) Sauve, S., McBride, M., Hendershot, W., 1998. Soil solution speciation of lead (II):
Effects of organic matter and pH. Soil Sci. Soc. Am. J. 62(3), 618-621.
70) Seo, Y.S., Hur, J., 2015. Investigation of adsorptive fractionation of humic acid on graphene oxide using fluorescence EEM-PARAFAC. Water Res. 73, 242-251.
71) Stedmon, C.A., Markager, S., Bro, R., 2003. Tracing dissolved organic matter in aquatic environments using a new approach to fluorescence spectroscopy. Mar.
Chem. 82, 239-254.
72) Swietlik, J., Laskowski, T., Kozyatnyk, I., 2015. Adsorption of Natural Organic Matter onto the Products of Water-Pipe Corrosion. Water Air. Soil Poll. 226(7), 1-9.
73) Summers, R.S., Roberts, P.V., 1988. Activated carbon adsorption of humic
112
substances. 1. Heterodisperse mixtures and desorption. J. Colloid Interface Sci.
122, 367-381.
74) Swift, R.S., 1996. Organic matter characterization. Methods of soil analysis. Part 3-chemical methods 1011-1069.
75) Thomas, G.W., 1996. Methods of soil analysis, Soil pH and soil acidity, Part 3.
475-479.
76) Thurman, E.M., 1985. Aquatic humic substances. In Organic geochemistry of natural waters. Springer Netherlands 273-361.
77) Umpleby, R.J., Baxter, S.C., Chen, Y., Shah, R.N., Shimizu, K.D., 2001.
Characterization of molecularly imprinted polymers with the Langmuir-Freundlich isotherm. Analytical chemistry 73(19), 4584-4591.
78) Urano, K., Yamamoto, E., Tsunatani, K., 1982. Granular activated carbon adsorption of humic acid. J. Japan Water Works Association 51(6), 37-47.
79) Wang, S.L., Mulligan, C.N., 2006. Effect of natural organic matter on arsenic release from soils and sediments into groundwater. Environ. Geochem. Health 28(3), 197-214.
80) Weng, L., Van Riemsdijk, W.H., Hiemstra, T., 2007. Adsorption of humic acids onto goethite: Effects of molar mass, pH and ionic strength. J. Colloid Interface Sci. 314(1), 107-118.
81) Yamashita, Y., Jaffe, R., Maie, N., Tanoue, E., 2008. Assessing the dynamics of dissolved organic matter (DOM) in coastal environments by excitation emission matrix fluorescence and parallel factor analysis (EEMǦPARAFAC). Limnol.
Oceanogr. 53(5), 1900-1908.
82) Yan, L., Fitzgerald, M., Khov, C., Schafermeyer, A., Kupferle, M.J., Sorial, G.A., 2013. Elucidating the role of phenolic compounds in the effectiveness of DOM adsorption on novel tailored activated carbon. J. Hazard. Mater. 262, 100-105.
83) Yang, L., Hur, J., Zhuang, W., 2015. Occurrence and behaviors of fluorescence EEM-PARAFAC components in drinking water and wastewater treatment systems and their applications: a review. Environ. Sci. Pollut. R. 22(9), 6500-6510.
84) Yang L., Shin, H., Hur, J., 2014. Estimating the Concentration and Biodegradability of Organic Matter in 22 Wastewater Treatment Plants Using Fluorescence
113
Excitation Emission Matrices and Parallel Factor Analysis. Sensors 14, 1771-1786.
85) Yu, H., Song, Y., Liu, R., Pan, H., Xiang, L., Qian, F., 2014. Identifying changes in dissolved organic matter content and characteristics by fluorescence spectroscopy coupled with self-organizing map and classification and regression tree analysis during wastewater treatment. Chemosphere 113, 79-86.
86) Zhu, G., Yin, J., Zhang, P., Wang, X., Fan, G., Hua, B., Ren, B., Zheng, H., Deng, L., 2014. DOM removal by flocculation process: Fluorescence excitation-emission matrix spectroscopy (EEMs) characterization. Desalination 346, 28-45.
87) Zsolnay, A., 2003. Dissolved organic matter: artefacts definitions and function.
Geoderma 113, 187-209.